Effect of Sensitization on Corrosion-Fatigue Cracking in Al 5083 Alloy

An investigation was carried out to characterize the effect of sensitization (or aging), environment (including [NaCl] concentration), and load ratio on fatigue crack growth and stress-corrosion cracking (SCC) of Al 5083 alloy. Both low and high load ratios, corresponding to R = 0.1 and R = 0.85 were examined. The results indicate: (1) fully sensitized Al 5083 has very low high stress-ratio (at R = 0.85) corrosion-fatigue (CF) threshold stress intensity ( Kth) and SCC threshold (K1SCC) in saltwater; (2) the as-received Al 5083-H131 has good CF and SCC resistance; (3) at 175 C aging temperature, high stress ratio Kth and K1SCC in saltwater decrease with increasing aging time up to about 240 hours; aging times longer than 240 hours produce little additional degradation; (4) sensitization has no effect on fatigue crack growth at low stress ratio of R = 0.1 in any environment, and no effect at any stress ratio in vacuum and in ambient air; (5) both high stress ratio Kth and K1SCC are influenced by [NaCl] concentration, higher [NaCl] results in a lower high stress ratio Kth and K1SCC.
The original document contains color images. Prepared in collaboration with the Center for Corrosion Science and Engineering, Chemistry Division, NRL, Washington, DC.